They considered how well the grocers did in areas such as corporate transparency, supply-chain initiatives, support for shoppers and food-donation programs. Then, they gave out letter grades.

It’s not a report card any parent would be pleased to see.

Grocers get mediocre scores

Various vegetables and fruits on display in a grocery store.(Photo: moodboard, Getty Images/moodboard RF)

No store got an A. Six got Ds or Fs.

One strength of American supermarkets is donating surplus food, the report found: All 10 had food-donation programs in place.

The overarching weakness was a lack of transparency. Only one company offered the public any information about food-waste volume. Without this data, the report says, supermarkets are keeping customers and investors in the dark.

“Grocers have the most power in the food supply system and cause waste in so many directions — at the store, producer, farm and even in the home,” said Jordan Figueiredo, who runs The "Ugly" Fruit and Veg Campaign.

“We hope that it influences them to not only report more about what they waste and what they’re doing to prevent it, but also to get them to do more to prevent waste from the start, up the supply chain.”

TAKE THIS QUIZ: HOW MUCH DO YOU KNOW ABOUT FOOD WASTE?

Who scored what?

Walmart: B

Ahold Delhaize U.S.: C

Kroger: C

Albertsons: C

Target: D

Trader Joe’s: D

Whole Foods Market: D

Costco U.S.: D

Publix: D

Aldi U.S.: F

The Center for Biological Diversity and the "Ugly" Fruit and Veg Campaign graded the 10 largest U.S. supermarkets on how they deal with food waste.(Photo: Grocerywaste.com)

Walmart was the best performer, with a B grade. The report found that Walmart was the only company to implement in-store programs such as “improving store fixtures, standardizing date labels and educating associates and shoppers.”

Ahold Delhaize, the Dutch retailer that operates brands such as Food Lion and Giant Food, earned a C. It was the only company out of the 10 that publicly reported its total food-waste volume.

Kroger, the country’s largest supermarket chain by revenue, got a C grade. The report found that Kroger, parent company of Fry's Food & Drug Stores, led the pack for company commitments because it was the only one to establish a goal of zero food waste by 2025. Three other companies had waste-reduction goals, but they were either later than 2025 or had smaller diversion targets.

Aldi, a German grocer, had the worst grade. With a F ranking, it was the only company that did not report a food-recycling program that uses unsold food as animal feed or for other industrial uses.

We asked Figueiredo what consumers can do to encourage supermarkets to improve their scores:

“Shop somewhere that takes better responsibility and action,” he said.